Environmental chambers are designed to provide accurate environmental control of temperature and relative humidity within the chamber for use in ICH pharmaceutical stability testing, genetic studies, chromatography tests, tissue culture studies and other research and development applications such as shelf life tests and packaging, paper products or electronic component breakdown, for example. Environmental chambers typically include a heating and refrigeration control system to control the temperature within the enclosed internal chamber and a humidification system to control the relative humidity within the chamber. The products placed within the enclosed chamber are subjected to a predetermined temperature and relative humidity over a period of time to determine the reaction of the product and/or its packaging to prolonged exposure to various temperature and relative humidity ranges.
In the past, environmental chambers have controlled the relative humidity within the chamber through humidification systems incorporating water spray nozzles or atomizers for example. The spray nozzles or atomizers are designed to inject water droplets into the air flow path of the chamber in which the water droplets are mixed with forced air generated from air outside of the enclosed chamber. The mixture of the water droplets and forced air produce a moist air that is introduced into the enclosed chamber to thereby control the relative humidity within the chamber.
Conventional spray nozzles and atomizers used in known environmental chambers typically form water droplets that are not uniform in size so that both smaller and larger water droplets are mixed with the forced air introduced into the enclosed chamber. The larger water droplets are not readily absorbed by the air within the chamber so that it is oftentimes difficult to precisely and reliably control the relative humidity within the chamber at a predetermined relative humidity set-point. Also, the larger droplets have a tendency to accumulate on the walls of the enclosed chamber and eventually the droplets form a puddle of water on the floor of the chamber which is undesirable.
Therefore, there is a need for an environmental chamber having a humidification system that provides for precise and reliable control of the relative humidity within the chamber.
There is also a need for an environmental chamber having a humidification system that provides for efficient humidification of the chamber air without causing undesirable accumulation of water droplets within the chamber.